Treatment of tumours

A steroid derivative selected from the group of compounds defined by formula (I) or (II) as shown below, wherein the only difference between said formulas is the bond between carbon number 5 and carbon number 6:

• wherein
• R1O is in the β-position and R1 is a hydrogen atom;
• an NO2, an SO3H, an OP(OH)3 an acyl group, or any other group that forms an ester with an inorganic or organic acid;
• a protecting group, such as CH3, CH2OMe, or CH2O-alkyl;
• an aliphatic chain which is straight or branched, saturated or unsaturated, or cyclic, including mixed cyclic and aliphatic substituents, which substituents are saturated or unsaturated, aromatic or heterocyclic and contains up to 20 carbon atoms, which substituents can be chosen from hydroxyl, any halogen, amino or alkylamino, carboxylic acid or carboxylic acid ester;
• R2 is R′O in β-position of carbon number 7 or can be (is) hydrogen in the case of formula (II);
• wherein R′ independently of R1, R3 or R4 can be any one of the groups defined above in relation to R1;
• R3 is in α-position and is a hydroxyl group, an acyl-group or an alkoxy group R″O, where R″ independently of R1, R3, or R4 can be any of the groups defined above in relation to R1;
• R4 is in β-position and is hydrogen, an alkyl group, an acyl group, or an alkoxy group of the formula R″″O, wherein R″′ can be any group mentioned for R1, independent of R1, R2, or R3, for use as a medicament.